Hydraulic shock absorber



June 20, 1944. W. ZENZ 2,352,063

HYDRAULIC sHo'cK ABsoRBER Filed Feb. 28, 1941 by .A

Patented June 20, 1944 HYDRAULIC SHOCK Ansonnn.

Wilhelm Zenz, Wuppertal-Elberfeld, Germany; vested in the Alien Property Custodian Application February 28, 1941, Serial In Germany July 3, 1930 12 Claims.

The present invention relates to a single acting or double acting hydraulic shock absorber particularly for deadening or dampening relative movements between the axis of a vehicle on the one hand and the chassis or underframe and the carriage body on the other hand. The invention consists in so constructing the shock absorber that it not only acts as absorber but over a certain range also as stabilizer without requiring the pipe connections between the absorber cylinders lat the two ends of the axis used ordinarily in .connection with hydraulic stabilizers. With the absorber according to the present invention a shock absorption Ais effected at the beginning in a first range of dampening, but on exceeding a certain amplitude, the vibrating motion is totally or nearly totally braked and only if a certain higher tension, exceeding the braking force, is again established-between the carriage body and the axis, that is to say, in a second range of dampening a further absorption of the vibrations is effected.

'Ifo4 obtain this object a liquid lled hollow space `is provided according to the invention in the absorber piston which hollow space is closed by a spring-loaded piston guided in the absorber piston', a throttling device for the liquid displaced from the hollowspace being provided either at the absorber piston or at the small piston.

. A- Vsubstantial featurer of the invention consists in this that the discharge opening for the liquid displaced'from the hollow space as well as the suction opening by which liquid is admitted again to the hollow space if the small piston returns discharge into the pressure space of the absorber. Herebythe following substantia1 dilerences in action and advantages result:

With slow movement of the small piston, for instance if the vehicle takes a curve, the liquid displaced from the hollow space flows into the pressurespace behind the absorber piston and here produces an overpressure which, however, is not yet suiiicient to open the high pressure valve arranged between the high pressure side and the ylow pressure side of the absorber, but is capable of displacing the large piston in adirection opposite to the movementj of the small piston so that the large piston moves towards the small piston. Consequently the small piston bears against the. inner .side ofthe bottom of the large piston earlier as would correspond to its normal stroke according to its starting position and the stabilizing begins earlier about this section of the stroke performed by the large piston which is very desirable. At fast movement of the small piston.

(Cl. 18S-88) ziol however, the liquid fromy the hollow space between the pistons is supplied with a jerk into the high pressure space and thehigh pressure valvev is forced open by the high pressure suddenly occurring, whereby the largepiston, due to its mass inertia, remains absolutely immovable. Between these two extreme possibilities explained a large number of intermediate steps are possible in which the large piston is moved towards the small piston as well as the high pressure valve is opened already.

The shock absorber according to the invention, therefore, has the advantage that the second range of dampening automatically begins in dependence on the velocity of the movement to b e dampened, i. e. an automatic control of the beginning and of the duration of the individual steps is obtained.

a further advantage of the shock absorber ac cording to the invention consists in this that by drawing the liquid out of the pressure-space of the shock absorber the danger is obviated that air reaches the hollowspace which otherwise by drawing liquid from a space chamber, easily may occur, for instance due to heavy vibrations of the vehicle or at low'liquid level. 'I'he total device therefore operates absolutely with largest uniformity and reliability.

Further details of the invention may be seen from the following specification given by way of the accompanying drawing .which shows one modification of the invention in a longitudinal section. Fig. 1 is a 1ongitudinalcentra1 sectional view througha shock absorber embodying my invention, Vand Fig. 2f is adetail elevation of the piston structure, taken substantially on the line 2-2 of Fig. l, looking inr the direction of the arrows. l

The shock-absorber consists of two cylinders, the high pressure cylinder I and the low pressure cylinder` 2 with pistons 3 and 4 respectively, the pistons 3 and 4 being connected for movement as a unit. In the pistons 3 and 4 which consist of `cylindrica1 sleeves with inserted'bottoms 9 and I 0 respectively held by retaining rings 'I and 8 respectively smaller piston II and I2 respectively areV guided which bear against the piston bottoms 9` and'fl by springs I3 and lI4 respectively. A cam lever 5 on the operating shaft 6 engages pistons II and I2 to displace the latter and' thereby to eiect displacement of pistons 3 and 4 as described. The hollow spaces I5 and I6 formed between the large pistons and the small pistons are connected to the high pressure space I1 and the low pressure space I8 respectively by a passage I9 and 20 respectively and the suction valves 2I and 22 (shifting valves) respectively. The valves 2l and 22 preferably are arranged in the exchangeable piston bottoms 9 and I0 respectively. To compensate for a liquid loss eventually occurring in the system, a suction valve 24 (snifting valve) leading to a spare chamber 23 is provided in the bottom of the piston I2. The passages I9 and 20 generally consist of smooth bores the diameter of which is from the beginning adapted to the weight of the vehicle and to the force acting upon the shock absorber respectively. A

The high pressure space I1 is connected by way of a passage 25 to the high pressure valve 26 which discharges into a passage 21, 28 leading to the low pressure space I8. On the other hand the low pressure valve 29 connected to the passage 28 discharges by way of the bore 30 into the passage 25. The just described deviceY acts in such a manner that at slow movements of the cam lever the pistons 3 and 4 move towards the pistons II and I2 respectively as indicated in the 'drawing by arrows. At fast movements of the pistons I I and I2, however, thepistons 3 and 4 remain at rest and the liquid discharged from the spaces I5 and I6 by way of the passages I9 and 20 respectively produces in the spaces Il and I8 such a pressure that the valves 25 and 29 are opened and thereby the liquid flows from the high pressure side to the low pressure side and vice versa respectively. i

The movement of the pistons II and I2 relatively ,to'the pistons 3 and 4 respectively is 'comp1eted as vsoon yas the pistons I I and I2 have covered the mouths of the passages I9 or 20 respectively.

As may be seen from the drawing, the valve casings 3|, 32 arranged at the exchangeable piston bottoms 9 and I0 respectively form a guide for the springs I3 and I4.

What I claim is:

1. An hydraulic shock absorber, comprising two cylinders, an absorber piston in each' of said cylinders, a liquid filled hollow spacein each of said absorber pistons closed by a spring-loaded piston guided in said `absorber piston, and a throttling device for the liquid discharged from said hollow space provided at one of said pistons, said throttling device discharging into the pressure space of the shock absorber, v y

2. An hydraulic shock absorber, comprising. two cylinders, an absorberipiston in each of said cylinders, a liquid filled hollow space in each of said absorber pistons'closed by a spring-loaded piston guided in said absorber piston, a throttling device for the liquid'discharged from said hollow space provided at one of said pistons and a shifting valve for drawing liquid into the hollow space between the two pistons, said throttling device as well as said snifting valve communicating with the pressure space of the shock absorber,

3. An hydraulic shock absorber as set forth in claim 2 in which the throttlingopening for the liquid displaced from the hollow space consists of a smooth passage provided inthe wall of said absorber piston. y

4. An hydraulic shock absorber as set forth in claim 1 in' which each of the absorber pistons consists of a cylindrical sleeve 'and an insertable piston bottom.

5. An hydraulic shock absorber as set forth in claim 2 in which each of the absorber pistons consists of a cylindrical sleeve and an insertable piston bottom.

6. An hydraulic shock absorber as set forth in claim 1 in which each of the absorber pistons consists of a cylindrical sleeve and an insertable piston bottom, each of said insertable piston bottoms simultaneously forming a casing for said snifting valves.

'7. An hydraulic shock absorber as set forth in claim 2 in which each of the absorber pistons consists of a cylindrical sleeve and in insertable piston bottom, each of said insertable piston bottoms simultaneously forming a casing for said snifting Valves.

8. An hydraulic shock absorber as set forth in yclaim 1 in which each of the absorber pistons v consists of a cylindrical sleeve and an insertable piston bottom, each of said insertable piston bottoms simultaneously forming a casing for said snifting valves and each of said valve casings forming a guide for the springs loading the pis'- tons.

9. An hydraulic shock absorber as set forth in claim 2 in which each of the absorber pistons consists of a cylindrical sleeve and an insertable piston bottom, each of said insertable piston bottoms simultaneously forming a casing for said shifting valves, and each of said valve casings forming a guide for the springs loading the pistons.

10. An hydraulic shock absorber, comprising two cylinders,-an absorber pistonin each of said cylinders, a liquid filled hollow space in each of said-absorber pistons closed by a spring-loaded piston guided in said absorber piston, a throttling device for the liquid discharged from said hollow space provided at one of said pistons and a snifting valve for drawing'liquid into the hollow space between the two pistons, each of the absorber pistons consisting of a cylindrical sleeve and an insertable piston bottom.

l1. An hydraulic shock absorber, comprising two cylinders, an absorber piston in each of said cylinders, a liquid lled hollow space in each of said absorber pistons closed by a spring-loaded piston guided in saidabsorber piston, a throttling device for the liquid discharged from said hollow space provided-at one of said pistons and a shifting valve for drawing liquidinto the hollow space between the -two pistons, each ofthe absorber pistons consisting. of a cylindrical sleeve and an insertable piston bottom, each of said insertable piston bottoms simultaneously forming a casing for said shifting valves. `f` 12. An hydraulic vshock absorber, comprising two cylinders, an absorber pistonin each of said cylinders, aliquid iilled hollow spacein-each of said absorberfpistons closed by a spring-loaded piston guided in saidabsorber piston, a throttling device for the liquid discharged from saidhollow space provided at one of said pistons and-a shifting valve for drawing 'liquid into the hollow space between the two pistonseach of the absorber pistons consisting. of ar cylindrical sleeve andan insertable piston bottomgeach of said insertable piston bottoms simultaneously formingl a casing for said snifting valves, and each of said valve casings forming a guide for the springs loading thepistons. l y

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